In the road-building art it is the practice to first rough grade stretches of the proposed roadbed to approximate the predetermined grade and slope by using manually controlled earth grading machines. These operations define the general path of the roadbed and fill in the major depressions or cut off the major elevations along the path and deposit comminuted earth in a fairly even fashion along the path traversed by the machinery. This generally requires several passes of the machinery and is an expensive initial operation.
Following the rough grading it is necessary to fine grade the roadbed to rather close tolerances for the purpose of providing a bed for deposit of the base materials on which the concrete slabs will be laid by paving machines. The fine grading machines are more sophisticated and include means for finite control of the grade and slope of the working tools which include augers, scrapers and screeds adapted to prepare the finished grade to close specifications.